Well to go through your XP computer you would need two NIC's and a crossover cable. You would set up internet connection sharing on the desktop, and then configure the IP's on the laptop and other NIC on your desktop.
However because it's a laptop, I don't know why you wouldn't want to go wireless. Just buy a wireless router and that will allow you to use the internet anywhere from within your house.
BTW, why did you block out your internal IP and subnet?